The present invention pertains to the field of insulating material and relates to a generally free flowing composition which may be either applied as a loose fill or granular like product or as a wet spray in conjunction with an adhesive. By variance of the ratio of the respective components, the insulation composition hereof may serve as a minimal heat insulator, on the one hand, or in the extreme, as a fire retardant wall.
The invention hereof has found particularly useful application in the interior of metallic buildings.
In relatively recent years, the advent of metallic building structures, primarily for small office buildings and warehouses, has noticeably replaced or supplemented conventional wooden building structures. These metallic building structures are not readily amenable to the same type of insulating materials and methods as has been commonly been used heretofore with other building structures. Conventional building structures have in the past frequently been insulated with a variety of known insulation materials, such as asbestos or glass fiber compositions, such as is shown in U.S. Pat. No. 3,687,850, where there is disclosed a fiber composition structure useful at temperatures of about 2,000.degree. F. and made out of silica and alumina fibers primarily. Fibers of this general type have heretofore been manufactured into thermal insulation compositions preformed into fiberglass batts or the like, and placed in sidewall cavities and attics. The fiberglass batts are sized to fit between upright studs in a wall cavity or horizontal joists in an attic. While such fiberglass batts provide good insulation properties, that is an R value (in hr-ft.sup.2 -F/BTU) of about 11 or 12, the installation of such fiberglass batts is not only difficult after construction of the building is completed, but sometimes, particularly in metal buildings or the like, is not feasible, because there may be no intermediate roof on which to lay the batt. Even if there is, it may become more desirable to simply "blow" the thermal insulation directly on the surface of the metal building, that is on the interior ceiling surface. This is quite acceptable, except where the heat insulation material contains the component of boric acid, a commonly used compound which is particularly corrosive to metal, and as a result, the boric acid must be neutralized or "buffered" with a chemical agent such a borax. The addition of borax to boric acid significantly increases the cost of the insulation material and adds relatively nothing to its principal objective, that is heat insulation. Now that the construction of metal buildings has risen dramatically and partially replaced conventional type building construction, and as a result significantly greater amounts of blown on insulation is being used, there is greater opportunity for economy and savings in construction if an improved thermal insulator were developed and in which the borax component were eliminated.
The present invention is thus directed to an improved thermal insulator in which borax and the like types of chemical buffers and/or neutralizers is eliminated. A principal advantage and feature of the invention thus exists in a thermal insulator having no per se chemical buffer or neutralizer.
A further feature and advantage of the invention exists in a thermal insulator composition providing improved thermal insulation as a result of the neutralizer ingredient itself.
A further feature and advantage of the invention resides in an improved insulator in which the buffer and/or neutralizer is an expanded glass.
A further feature and advantage of the invention resides in an insulating material in which the thermal transmission properties may be varied predictably by variance of the ratio of the constant composition components.
Yet another feature and advantage of the invention is an improved thermal insulator in which the heat transmission characteristics may be varied by adjustment of the ratio of the component ingredients so that heat insulation can be minimized and so that heat insulation can be maximized, the latter to the extent of presenting a substantial fire wall insulator.
Yet another feature and advantage of the invention resides in an insulating material which is less expensive than materials presently used while yet improving the overall heat insulating characteristics per unit of thickness thereof and which is granular in form so as to constitute that which is commonly referred to as "loose fill".